i feel horrible

i broke up with my boyfriend about a month ago. i wasn’t happy in our relationship. he would always put me told. he told me that i needed to gain weight and stuff like that. and im not even skinny. im on the thick side. but after the breakup i got emotional support from one of his good friends. and one day some sexual things happened. and they keep happening. but we haven’t had sex. he’s not happy in his relationship anymore and i think he’s about to leave her. i think that he really likes me and does it make me a bad person if i would date one of my ex boyfriends good friends?